Semiconductor device with multi-layer metallization

ABSTRACT

One or more embodiments are related to a semiconductor device, comprising: a metallization layer comprising a plurality of portions, each of the portions having a different thickness. The metallization layer may be a final metal layer.

RELATED APPLICATION(S)

This is a divisional of U.S. patent application Ser. No. 11/859,799,filed on Sep. 24, 2007, entitled “Semiconductor Device with Multi-LayerMetallization”, which is hereby incorporated herein by reference in itsentirety.

FIELD OF THE INVENTION

Generally, the present invention relates to semiconductor devices andmethods of making semiconductor devices. More particularly, the presentinvention relates to metallization technology.

BACKGROUND OF THE INVENTION

Chips in certain technologies may include electronic devices andcircuits that may require final or top metal lines having a relativelylarge thickness. However, the same chip may also include electronicdevices and circuits may require final or top metal lines with arelatively fine pitch.

SUMMARY OF THE INVENTION

An embodiment of the invention is a semiconductor device, comprising: ametallization layer comprising at least a first metal line and a secondmetal line spacedly disposed from the first metal line, the first metalline having a first thickness, the second metal line having a secondthickness greater than the first thickness. In one or more embodiments,the metallization layer may be a final metal layer.

An embodiment of the invention is a semiconductor device, comprising: ametallization layer comprising a plurality of portions, each of theportions having a different thickness. In one or more embodiments, themetallization layer may be a final metal layer.

An embodiment of the invention is a semiconductor structure, comprising:a metal layer comprising at least one metal line, the metal linecomprising a plurality of portions, each of the portions having adifferent thickness. In one or more embodiments, the metal layer may bea final metal layer and the metal line may be a final metal line.

An embodiment of the invention is a method for forming a final metallayer of semiconductor device, comprising: providing a surface; forminga first metal layer over a portion of the surface; and forming a secondmetal layer over at least a portion of the first metal layer and/or overa portion of the surface that is not occupied by the first metal layer.

An embodiment of the invention is a method for forming a semiconductordevice, comprising: providing a metal seed layer; first electroplating afirst metal layer over the metal seen layer; and second electroplating asecond metal layer over the first metal layer.

BRIEF DESCRIPTION OF THE DRAWINGS

FIGS. 1 through 10 provide an embodiment of a method of making anembodiment of a semiconductor device;

FIGS. 11 through 13A provide an embodiment of a method of furtherprocessing the semiconductor device from FIG. 10; and

FIG. 13B provides an embodiment of a semiconductor device;

FIG. 13C provides an embodiment of a semiconductor device;

FIG. 14 provides an embodiment of a semiconductor device;

FIG. 15A through 15D shows an embodiment for making an embodiment of asemiconductor device;

FIGS. 16A through 16D shows an embodiment for making an embodiment of asemiconductor device;

FIGS. 17A through 17D shows an embodiment for making an embodiment of asemiconductor device;

FIGS. 18A through 18D show an embodiment of a method of making anembodiment of a semiconductor device;

FIG. 19 shows an embodiment of a semiconductor device;

FIG. 20A shows an embodiment of a final metal layer;

FIG. 20B shows an embodiment of a final metal layer;

FIG. 20C shows an embodiment of a final metal layer;

FIG. 20D shows an embodiment of a final metal layer;

FIG. 20E shows an embodiment of a final metal layer;

FIG. 20F shows an embodiment of a final metal layer; and

FIG. 20G shows a cross sectional view of an embodiment of asemiconductor device.

DETAILED DESCRIPTION OF THE INVENTION

The following detailed description refers to the accompanying drawingsthat show, by way of illustration, specific details and embodiments inwhich the invention may be practiced. These embodiments are described insufficient detail to enable those skilled in the art to practice theinvention. Other embodiments may be utilized and structural, logical,and electrical changes may be made without departing from the scope ofthe invention. The various embodiments are not necessarily mutuallyexclusive, as some embodiments can be combined with one or more otherembodiments to form new embodiments.

FIGS. 1 through 10 provide an embodiment of a method of making anembodiment of a semiconductor device. FIG. 1 shows a semiconductorstructure 100 of an embodiment of a partially completed semiconductorchip or device. The structure 100 comprises a substrate 210. In one ormore embodiments of the invention, the substrate 210 may be a p-typesubstrate. However, more generally, in one or more embodiments of theinvention, the substrate may be a silicon substrate or other suitablesubstrate. The substrate may be a silicon-on-insulator (SOI) substrate.The SOI substrate may, for example, be formed by a SIMOX process. Thesubstrate may be a silicon-on-sapphire (SOS) substrate. The substratemay be a silicon-on-germanium substrate.

Formed over the substrate 210 is a layer 220. The layer 220 may itselfcomprise one or more levels of metallization layers, inter-leveldielectric layers, vias, plugs etc. The combination of the layer 210 andlayer 220 may be viewed as a workpiece or a support structure for thedeposition of additional layers over such a workpiece or support. In oneor more embodiments, a top portion of the layer 220 may comprise aninter-level dielectric layer having vias and plugs.

Referring to FIG. 1, a barrier layer 230 may be formed over the layer220. The barrier layer 230 may comprise a conductive material. Thebarrier layer 230 may comprise a metallic material. The barrier layer230 may comprise one or more of the elements from the group consistingof Ti, Ta, N and W. The barrier layer 230 may comprise a Ti-basedmaterial or a Ta-based material. The barrier layer 230 may comprise oneor more materials selected from the group consisting of TiW, WN, TiN,and TaN. The barrier layer may be formed as a composite or as adual-layered system such as a titanium/TiN or a tantalum/TaN dual-layer.The barrier layer 230 may serve to lower or prevent diffusion betweenthe materials that are on opposites sides of the barrier layer. Thebarrier layer 230 may be deposited by a chemical vapor deposition (CVD)or a physical vapor deposition (PVD) process.

Again referring to FIG. 1, a metal seed layer 240 may be formed over thebarrier layer 230. The metal seed layer 240 may be formed by asputtering process or by a chemical vapor deposition (CVD) process. Inone or more embodiments, the thickness of the metal seed layer may beabout 5000 angstroms or less. In another embodiment, the thickness maybe about 2000 angstroms or less. In another embodiment, the thicknessmay be about 1000 angstroms or less.

Referring to FIG. 2, a galvanic resist 250 may be formed over the metalseed layer 240. The galvanic resist 250 may be applied by a spin onprocess. Suitable galvanic resists are available commercially. Referringto FIG. 3, the galvanic resist 250 may be patterned and a portion may beremoved from particular locations over the metal seed layer 240.

Referring to FIG. 4, a first metal layer 260 may be deposited over themetal seed layer in places where the portions of galvanic resist wereremoved. Generally, the thickness of the first metal layer 260 is notlimited to any particular thickness. In one or more embodiments, thefirst metal layer 260 may have a thickness of about 2000 nm or less. Inone or more embodiments, the first metal layer 260 may have a thicknessof about 1000 nm (1000 nanometers) or less. In one or more embodiments,the first metal layer 260 may have a thickness of about 500 nm or less.In one or more embodiments, the first metal layer 260 may have athickness of about 250 nm or less. In one or more embodiments, the firstmetal layer 260 may have a thickness of about 200 nm or less. In one ormore embodiments, the first metal layer 260 may have a thickness ofabout 150 nm or less. The thickness of the first metal layer 260 isshown as thickness T₂₆₀ in FIG. 4.

The first metal layer 260 may be formed by an electroplating process. Asa possible example of an electroplating process, pure copper may beelectroplated by placing a wafer (which may, for example, have a layeredarrangement similar to that shown in FIG. 3) into a solution of, forexample, copper sulfate containing copper ions. The wafer (with a seedlayer) may be electrically coupled to a power supply to form a cathode.A solid piece of pure copper may be placed in the solution andelectrically coupled to the power supply to form an anode. At thecathode, copper ions are reduced to metallic copper. At the anode, thepure copper is oxidized. Other electroplating processes are, of course,possible. In other embodiments, other metallic materials (such a copperalloys) may be electroplated.

In the embodiment shown in FIG. 4, the first metal layer 260 is formedat about the height of the galvanic resist 250. However, in one or moreembodiments, the first metal layer may be formed to a height which isbelow the height of the galvanic resist. In one or more embodiments, thefirst metal layer 260 may be formed to a height which is above theheight of the galvanic resist 250.

Referring to FIG. 5, after the first metal layer 260 is formed, theremaining galvanic resist 250 may be removed. Referring to FIG. 5, it isseen that a first metal layer 260 may be formed which comprises fourspacedly disposed first metal layer portions 260A-D of the first metallayer 260. In one or more embodiments, a first metal layer 260 may beformed which comprises only a single continuous portion. In one or moreembodiments, a first metal layer 260 may be formed which includes aplurality of spacedly disposed portions. In one or more embodiments, twoor more first metal layer portions may have a distance between themwhich is less than about 600 nm. In another embodiment, the first metallayer portions may have a distance between them which is less than about500 nm. As an example, the first metal layer portions may have adistance between them which is about 400 nm. The thickness of firstmetal layer 260 is also shown as thickness T₂₆₀ in FIG. 5. Each of thespacedly disposed portions 260A-D may be viewed as a separate metalline.

Referring to FIG. 6, a second layer of galvanic resist 270 may be formedover the structure from FIG. 5. Referring to FIG. 6, the galvanic resist270 may then be patterned (where portions of the galvanic resist areremoved) to form the structure shown in FIG. 7. Referring to FIG. 7, itis seen that portions of the galvanic resist 270 have been removed sothat openings 272 are formed overlying top surfaces of the first metallayer 260 where a second metal layer will be deposited. In particular,it is seen that openings 272 are formed so as to expose at least aportion of the top surface of each of the first metal layer portions260A and 260D. The first metal layer portions 260B and 260C are leftcovered by the galvanic resist.

Referring to FIG. 8, a second metal layer 280 may then be depositedwithin the openings 272 formed in the galvanic resist. In the embodimentshown, the second metal layer 280 is disposed over and in electricalcontact with the first metal layer portion 260A and the first metallayer portion 260D. The deposition of the second metal layer 280 may beformed using an electroplating process. In the embodiment shown, theheight of the second metal layer 280 is level with the height of theresist 270. However, in other embodiments it is possible that the secondmetal layer 280 is deposited below the top surface of the resist 270 orthat is it deposited above the top surface of the resist 270.

In one or more embodiments, the thickness of the second metal layer 280(shown as thickness T₂₈₀ is FIG. 8) may be greater than the thicknessT₂₆₀ of the first metal layer 260. In one or more embodiments, thethickness of the second metal layer 280 may be less than the thicknessof the first metal layer 260. In one or more embodiments, the thicknessof the second metal layer 280 may be about the same as the thickness ofthe first metal layer 260.

In one or more embodiments, the thickness T₂₈₀ of the second metal layer280 may be at least 2 times as large as the thickness of the first metallayer 260. In one or more embodiments, the thickness of the second metallayer 280 may be at least 5 times as large as the thickness of the firstmetal layer 260. In one or more embodiments, the thickness of the secondmetal layer 280 may be at least 10 times as large as the thickness ofthe first metal layer 260. In one or more embodiments, the thickness ofthe second metal layer 280 may be at least times as large as thethickness of the first metal layer 260. In one or more embodiments, thethickness of the second metal layer 280 may be at least 100 times aslarge as the thickness of the first metal layer 260.

In one or more embodiments, the thickness of the second metal layer 280may be about 1000 nm or greater. In one or more embodiments, thethickness of the second metal layer may be about 1500 nm or greater. Inone or more embodiments, the thickness of the second metal layer 280 maybe about 2000 nm or greater. In one or more embodiments, the thicknessof the second metal layer may be about 2500 nm or greater. In one ormore embodiments, the thickness of the second metal layer 280 may beabout 3000 nm or greater. In one or more embodiments, the thickness ofthe second metal layer may be about 5000 nm or greater. In one or moreembodiments, the thickness of the second metal layer may be about 10000nm or greater. In one or more embodiments, the thickness of the secondmetal layer may be about 20000 nm or greater.

In the embodiment shown FIG. 8, the second metal layer 280 is depositedover the two spacedly disposed first metal layer portions 260A,D to formtwo metal lines M2 having a thickness T2. As shown, a portion 280A ofthe second metal layer 280 is deposited over the portion 260A of firstmetal layer 260 to form a first metal line M2. Likewise, a portion 280Bof the second metal layer 280 is deposited over the portion 260B offirst metal layer 260 for form a second metal line M2. The remaining twofirst metal layer portions 260B,C form metal lines M1 having a thicknessT1 which is equal to the thickness T₂₆₀ of the first metal layer. Thethickness T2 of metal lines M2 is greater than the thickness T1 of metallines M1. Hence, two groups of metal lines are formed. A first group ofmetal lines are the metal lines M1. These metal lines include the firstmetal layer 260 but not the second metal layer 280. A second group ofmetal lines are the metal lines M2. These metal lines include the firstmetal layer 260 and the second metal layer 280. In the embodiment shown,the metal lines M2 are thicker than the metal lines M1.

In an embodiment of the invention, there may be at least one thickermetal line and at least one thinner metal line (where a thicker metalline is thicker than a thinner metal line). In an embodiment of theinvention, there may be a plurality of thicker metal lines. In anembodiment of the invention, there may be a plurality of thinner metallines.

In one or more embodiments, the metal lines M1 may have a thickness T1of about 2000 nm or less. In one or more embodiments, the thickness T1may be about 1000 nm or less. In one or more embodiments, the thicknessT1 may be about 500 nm or less. In one or more embodiments, thethickness T1 may be about 250 nm or less. In one or more embodiments,the thickness T1 may be about 200 nm or less. In one or moreembodiments, the thickness T1 may be about 150 nm or less.

In one or more embodiments, the metal lines M2 may have a thickness T2of about 500 nm or greater. In one or more embodiments, the metal linesM2 may have a thickness T2 of about 1000 nm or greater. In one or moreembodiments, the thickness T2 may be about 1500 nm or greater. In one ormore embodiments, the thickness T2 may be about 2000 nm or greater. Inone or more embodiments, the thickness T2 may be about 2500 nm orgreater. In one or more embodiments, the thickness T2 may be about 3000nm or greater. In one or more embodiments, the thickness T2 may be about5000 nm or greater. In one or more embodiments, the thickness T2 may beabout 10000 nm or greater. In one or more embodiments, the thickness T2may be about 20000 nm or greater.

In one or more embodiments, the thickness T2 of the metal lines M2 maygreater than the thickness T1 of the metal lines M1. In one or moreembodiments, the thickness T2 may be at least 2 times as large as thethickness T1. In one or more embodiments, the thickness T2 may be atleast 5 times as large as the thickness T1. In one or more embodiments,the thickness T2 may be at least 10 times as large as the thickness T1.In one or more embodiments, the thickness T2 may be at least 20 times aslarge as the thickness T1. In one or more embodiments, the thickness T2may be at least 50 times as large as the thickness T1. In one or moreembodiments, the thickness T2 may be at least 100 times as large as thethickness T1.

Referring to FIG. 8, each of the metal lines M1 have a width W1 whileeach of the metal lines M2 have a width W2. In the embodiment shown, thewidth W2 of the thicker lines M2 is greater than the width W1 of thethinner lines M1 (so that W2>W1). However, this does not have to be thecase so that it is also possible that the thicker lines M2 have asmaller width that the thinner lines M1 (so that W2<W1). It is alsopossible that the thinner lines M1 and the thicker lines M2 have thesame width (so that W1=W2). Likewise, it is possible that the thickerlines M2 may each have a different width and/or the thinner lines M1 mayeach have a different width.

In the embodiment shown in FIG. 8, the distance between the two metallines M1 is less than the distance between the two metal lines M2.However, this does not have to be the case. In one or more embodiments,the thinner metal lines M1 may have a finer pitch than the thicker metallines M2, but this does not have to be the case.

In one or more embodiments, the distance between metal lines M1 may beabout 600 nm or less. In one or more embodiments, the distance betweenmetal lines M1 may be about 500 nm or less. In one or more embodiments,the distance between metal lines M1 may be about 400 nm or less.

In one or more embodiments, the distance between metal lines M2 may beabout 800 nm or more. In one or more embodiments, the distance betweenmetal lines M2 may be about 1000 nm or more. In one or more embodiments,the distance between metal lines M2 may be about 1500 nm or more.

Referring to FIG. 9, after the deposition of the second metal layer 280,the remaining portion of the galvanic resist may be removed. Referringto FIG. 10, after the galvanic resist is removed, in one embodiment ofthe invention, a portion of the barrier material 230 and the metal seedmaterial 240 which is not underlying the material of the metal lines M2or the material of the metal lines M1 may be removed. Removing theseportions of the barrier material and the seed material serves toelectrically isolate each of the metal lines from the other metal lines.The removal may be accomplished by an etching process. The etchingprocess may be an anisotropic etching process. The etching process maybe a wet etch or a dry etch.

At this point in the process, there are several different ways toproceed to continue the process. Referring to FIG. 11, after the thickand thin metal lines are electrically isolated from each other, aprotective passivation layer 290 is deposited over the structure of FIG.10 to form the structure shown in FIG. 11. Generally, the passivationlayer 290 may be formed of any dielectric material. In one embodiment,the passivation layer 290 may comprise an imide such as a polyimide. Inother embodiments, the passivation layer 290 may comprise an oxide, anitride or an oxynitride. The passivation layer may, for example, beformed of silicon dioxide, silicon nitride, a silicon oxynitride orcombinations thereof. In one or more embodiments, the passivation layer290 may comprise one or more materials selected from the groupconsisting of SiN, SiON, SiC, SiO, SiO₂, and combinations thereof.

Referring to FIG. 12, after the passivation layer 290 is formed,openings 292 may be formed in the passivation layer so that the metallines M2 as well as the metal lines M1 are exposed. Referring to FIG.13A, a passivation material 295 may then be disposed within each of theopenings and on top of the exposed metallic material of each of themetal lines. The passivation material may comprise a metallic material.The passivation material 295 may be a single layer of a metallicmaterial. The passivation material may include two or more layers ofdifferent materials. For example, the passivation material may includetwo layers such as NiP/Pd (a Pd layer over a NiP layer) or NiMoP/Pd (aPd layer over a NiMoP layer). As another example, the passivationmaterial may include three layers such as NiP/Pd/Au (an Au layer over aPd layer over a NiP layer) or NiMoP/Pd/Au (an Au layer over a NiMoPlayer over a NiMoP layer). It is possible that more than three layers beused.

In the embodiment shown in FIG. 13A, openings are formed to expose themetal lines M2 and the metal lines M1. In one or more embodiments,openings 295 may be formed only to expose the metal lines M2 and not themetal lines M1. This is shown in FIG. 13B. Likewise, in one or moreembodiments, openings 295 may be formed only to expose the metal linesM1 and not the metal lines M2. This is shown in FIG. 13C. Also, in oneor more embodiments, openings may be formed to only to expose a portionof metal lines M2 and/or to only to expose a portion of the metal linesM1.

FIG. 14 shows another way of continuing the process from what is shownin FIG. 10. Referring FIG. 14, the metal lines M1, M2 may be passivatedby a passivation material 395. The passivation material 395 may besubstantially conformally deposited over the metal lines M1 and M2 aswell as over the sidewall surfaces of the seed layer 240 and thesidewall surfaces of the barrier layer 230. The passivation material 395may not remain on the sidewall surfaces of the barrier layer 230 so itis not shown over these surfaces in FIG. 14. In another embodiment, itis possible that the passivation layer 395 may also remain on thesidewall surfaces of the barrier layer 230.

In one or more embodiments, the passivation material 395 may compriseone or more metallic materials. The passivation material 395 may, forexample, be a single layer of a metallic material or it may comprise twoor more layers of different metallic materials. Examples of passivationlayers include Ni, NiPd, NiP, Ni/Pd (a dual layer), NiP/Pd (a duallayer), NiP/Pd/Au (a tri-layer), NiMoP, CoW, CoWP, NiMoP/Pd, Ni, Ni/Pd.A first layer may, for example, be an NiP layer (or an NiMoP layer, oran NiMoP layer, or a CoWP layer or a CoW layer, etc). This first layermay have a thickness of at least 300 nm. In one or more embodiments, thethickness of the first layer may be between about 500 nm and about 5000nm. A second metallic layer may be formed on top of the first metalliclayer (which may, for example, be a layer of NiP). The second metalliclayer may be a Pd layer. This second metallic layer may have a thicknessof about 100 nm or greater. In one or more embodiments, the secondmetallic layer may have a thickness of about 100 nm to about 500 nm.Over the second layer, we place a third metallic layer. The thirdmetallic layer may be a layer of silver or silver alloy. This thirdmetallic layer may have a thickness of about 100 nm or less. In one ormore embodiments, the third layer may have a thickness of about 50 nm orless. The first, second and third layers form a sandwich of materials.This sandwich may be a NiP/Pd/Au sandwich.

Referring again to FIG. 10, in another embodiment, it is possible themetal lines M1, M2 are not passivated at all.

Referring, to FIGS. 13A,B,C or to FIG. 14, it is seen that, in one ormore embodiments, two electrically isolated thinner metal lines M1 andtwo electrically isolated thicker metal lines M2 are formed. Moregenerally, in one or more embodiments, one or more thicker metal linesmay be formed and, one or more thinner metal lines may be formed wherethe thicker metal lines are thicker than the thinner metal lines. In oneor more embodiments, two or more of the metal lines may be spacedlydisposed for each other. In one or more embodiments, two or more of themetal lines may be electrically isolated from each other. In one or moreembodiments, two or more of the metal lines may be electrically coupledtogether.

The thicker and the thinner metal lines may all be part of the finalmetal layer of a semiconductor device. Hence, a final metal layer for asemiconductor device or semiconductor chip may be formed which comprisesat least a first metal layer and a second metal layer formed after thefirst metal layer. In one or more embodiments, the first and secondmetal layers may form a plurality of metal lines. In one or moreembodiments, the metal lines may be spacedly disposed from each other(for example, they may be physically spaced apart from each other). Oneor more of the metal lines may have a first thickness while one or moreof the metal lines may be have a second thickness which is thicker thanthe first thickness.

As part of a final metal layer (also referred to as a top metal layer),in one or more embodiments, it is possible that the thin metal lines maybe used for logic applications while the thick metal lines may be usedfor power applications. The thick and thin metal lines which are part ofthe final or top metal layer may be referred to as final metal lines ortop metal lines. Hence, the final metal layer may include at least onethinner final metal line and at least one thicker final metal line wherethe thicker lines have a thickness greater than the thinner lines.

It is noted that the process described above shows the formation of afinal metal layer having one or more final metal lines with a firstthickness and one or more final metal lines with a second thicknessgreater than the first thickness. However, the process may be continuedby forming (such as by a growth process or a deposition process) one ormore additional metal layers (possibly, for example, by depositingadditional layers of galvanic resist, patterning these layers and usingan electroplating process to deposit additional metal layers). A finalmetal layer may be formed which comprises a plurality of final metallines. The plurality of final metal lines may have a plurality ofthicknesses. The plurality of final metal lines may be spacedly disposedfrom each other. At least two of the plurality of final metal lines maybe electrically isolated from each other. At least two of the pluralityof final metal lines may be electrically coupled to each other.

Referring again to the embodiments shown in FIG. 8, FIG. 12 or in FIGS.13A through 13C, it is seen that in the embodiment shown, the metallines M2 are formed so that the portion 260A of first metal layer 260completely underlies the portion 280A of second metal layer 280.Likewise, the portion 260B of the first metal layer 260 completelyunderlies the portion 280B of the second metal line 280.

Another embodiment is shown in FIG. 15D where the second metal layer 280only partially overlies the first metal layer portion 260A. (Of course,in yet another embodiment, the second metal layer 280 may made wider sothat all of the portion 260A underlies the layer 280). In the embodimentshown in FIG. 15D, the metal line M1 includes the first metal layerportion 260B but does not include any portion of the second metal layer280. The metal line M1 has a thickness T1. The metal line M3 includesthe first metal layer portion 260A as well as the second metal layer280. The metal line M3 has a thickness T3. The thickness T3 of metalline M3 is greater than the thickness T1 of the metal line M1. FIG. 15Dshows how the metal lines M1 and M3 may be electrically isolated fromeach other by etching through the barrier layer 230 and seed layer 240.FIG. 15D further shows passivation layer 290 and passivation layer 295.The metal lines M1, M3 may also be passivated in a way which is similarto that shown in FIG. 14.

FIGS. 15A through 15D describes an embodiment for a method of making theembodiment shown in FIG. 15D. FIG. 15A shows that the first metal layer260 comprises spacedly disposed first layer portions 260A and 260B.These first layer portions 260A, 260B may be formed in a manner similarto that shown in FIGS. 1 through 5. Referring to FIG. 15B, a galvanicresist 270 may be formed over the structure from FIG. 15A. An opening272 may be formed in the resist. A second metal layer 280 may be formedwithin the opening. This may be done using an electroplating process.The second metal layer 280 partially overlies the portion 260A of firstmetal layer 260. A portion of layer 280A is also formed on the seedlayer 240. As shown in FIG. 15C, the galvanic resist 272 may then beremoved. Referring to FIG. 15D, the seed layer 240 and the barrier layer230 may then be etched at certain locations so that the metal lines M1and M3 become electrically isolated. A passivation layer 290 may then beformed over the structure, an opening 292 may be formed over the secondmetal layer 280 and a passivation layer 295 may be formed.

In the embodiment shown in FIG. 15C, the metal line M3 has a width W3and a thickness T3. The metal line M1 has a width W1 and a thickness T1.In one or more embodiments, the width W3 may be greater than the widthW1. In one or more embodiments, the width W3 may be less than the widthW1. In one or more embodiments, the width W3 may be equal to the widthW1.

Another embodiment is shown in FIG. 16D where the second metal layer 280is spacedly disposed from the first metal layer 260. In the embodimentshown in FIG. 16D, the metal line M1 includes the first metal layer 260but does not include any portion of the second metal layer 280. Themetal line M1 has a thickness T1. Likewise, metal line M4 includes thesecond metal layer 280 but does not include any portion of the secondmetal layer 280. The metal line M4 has a thickness T4. The thickness T4of the metal line M4 is greater than the thickness T1 of the metal lineM1. FIG. 16D shows how the metal lines M1 and M4 may be electricallyisolated from each other by etching through the barrier layer 230 andseed layer 240. FIG. 16D further shows passivation layer 290 andpassivation layer 295. The metal lines M1, M4 may also be passivated ina way which is similar to that shown in FIG. 14.

FIGS. 16A through 16D describes an embodiment for a method of making theembodiment shown in FIG. 16D. FIG. 16A shows a first metal layer 260.This layer may be formed by an electroplating approach similar to thatshown in FIGS. 1 through 5. Referring to FIG. 16B, a galvanic resist 270may be formed over the structure from FIG. 16A. An opening 272 may beformed in the resist. A second metal layer 280 may be formed within theopening. This may be done using an electroplating process. The secondmetal layer 280 is formed on the seed layer 240 but not on the firstmetal layer 260. As shown in FIG. 16C, the galvanic resist 270 may thenbe removed. Referring to FIG. 16D, the seed layer 240 and the barrierlayer 230 may then be etched at certain locations so that the metallines M1 and M4 become electrically isolated. A passivation layer 290may then be formed over the structure, an opening 292 may be formed overthe second metal layer 280 and a passivation layer 295 may be formed. Inthe embodiment shown in FIGS. 16A through 16D, the first layer 260 wasdeposited before the second layer 280. However, in another embodiment,it is possible that the layer 280 (the thicker one) is deposited beforelayer 260 (the thinner one).

In the embodiment shown in FIG. 16C, the metal line M4 has a width W4and a thickness T4. The metal line M1 has a width W1 and a thickness T1.In one or more embodiments, the width W4 may be greater than the widthW1. In one or more embodiments, the width W4 may be less than the widthW1. In one or more embodiments, the width W4 may be equal to the widthW1.

Another embodiment is shown in FIG. 17D where there are two spacedlydisposed metal lines M4 and M3. In the embodiment shown in FIG. 17D, themetal line M4 comprises the second metal layer 280 but not the firstmetal layer 260. The metal line M4 has a thickness T4.

Referring to FIG. 17C, the second metal line M3 comprises the firstmetal layer 260 and the portion 280B of the second metal layer 280.Metal line M3 comprises a first portion P1 that includes the first metallayer 260 but not the second metal layer 280. This portion P1 has athickness T₂₆₀ of the first metal layer 260. The metal line M3 comprisesa second portion P2 that includes the second metal layer 280 but not thefirst metal layer 260. This second portion P2 has a thickness T₂₈₀ whichis the thickness of the second metal layer 280. The metal line M3 has athird portion P3 which includes the first metal layer 260 and the secondmetal layer 280. The portion P3, shown in FIG. 17C, is that portion ofmetal line M3 where the second metal layer 280 overlies the first metallayer 260. The thickness of the portion P3 is the sum of the thicknessT₂₆₀ of first metal layer 260 and the thickness T₂₈₀ of second metallayer 280. This is shown as thickness T_(OVERLAP). The thickness T3 ofthe metal line M3 is the maximum of the thicknesses of each of theportions P1, P2 and P3. Hence, the metal line M3 has a thickness T3which is equal to the thickness T_(OVERLAP).

In the embodiment shown in FIG. 17C, the metal line M3 has threeportions where each portion has a different thickness. In the embodimentshown in FIG. 17C, the thickness of metal line M3 changes in thedirection along the width of the metal line.

It is noted that this discuss of metal line M3 as shown in FIGS. 17C and17D is also true for the metal line M3 shown in FIGS. 15C and 15D.

FIGS. 17A through 17D describes an embodiment for a method of making theembodiment shown in FIG. 17D. FIG. 17A shows a first metal layer 260.This layer may be formed by an electroplating approach similar to thatshown in FIGS. 1 through 5. Referring to FIG. 17B, a galvanic resist 270may be formed over the structure from FIG. 17A. Openings 272A and 272Bmay be formed in the resist. A second metal layer 280 may be formedwithin each of the openings. Portion 280A is formed in opening 272A.Portion 280B is formed in opening 272B. This may be done using anelectroplating process. As shown in FIG. 17C, the galvanic resist 270may then be removed. Referring to FIG. 17D, the seed layer 240 and thebarrier layer 230 may then be etched at certain locations so that themetal lines M3 and M4 become electrically isolated from each other. Apassivation layer 290 may then be formed over the structure, an opening292 may be formed over the second metal layer 280 and a passivationlayer 295 may be formed.

In the embodiment shown in FIG. 17C, the metal line M3 has a width W3and a thickness T3. The metal line M4 has a width W4 and a thickness T4.In one or more embodiments, the width W4 may be greater than the widthW3. In one or more embodiments, the width W4 may be less than the widthW3. In one or more embodiments, the width W4 may be equal to the widthW3.

Another embodiment is shown in FIG. 18D where there are two spacedlydisposed metal lines M1 and M5. In the embodiment shown in FIG. 18D, themetal line M5 comprises the second metal layer 280 as well as a thirdmetal layer. The metal line M1 comprises the first metal layer 260 butnot the second metal layer 280 and not the third metal layer 330. In theembodiment shown, the metal line M5 has a thickness T5 that is largerthan the thickness T1 of the metal line M1.

FIGS. 18A through 18D describes an embodiment for a method of making theembodiment shown in FIG. 18D. FIG. 18A shows a first metal layer 260 anda second layer 280. These layers may be formed by two electroplatingsteps: one for layer 260 and one for layer 280. This may be done usingprocessing steps similar to those described for FIGS. 1 through 8.Referring to FIG. 18B, a galvanic resist 270′ may be formed over thestructure from FIG. 18A. Opening 272′ may be formed in the resist 270′over the metal layer 280.

Referring to FIG. 18C, an electroplating process may then be used toform a third metal layer 330 over a top surface of the second metallayer 280. Referring to FIG. 18D, the barrier layer 230 and seed layer240 may be etch through and the galavanic resist 270′ may be removed. Apassivation layer 290 may be applied.

Hence, referring to FIGS. 18C and 18D, it is seen that two metal linesare formed by the process. These are metal line M1 and metal line M5.The metal line M1 includes the first metal layer 260 but not the secondmetal layer 280 or the third metal layer 330. A metal line M5 is formedthat include a second metal layer 280 and a third metal layer 330.

In the embodiment shown in FIG. 18C, the metal line M5 has a width W5and a thickness T5. The metal line M1 has a width W1 and a thickness T1.In one or more embodiments, the width W5 may be greater than the widthW1. In one or more embodiments, the width W5 may be less than the widthW1. In one or more embodiments, the width W5 may be equal to the widthW1.

The third metal layer 330 shown in FIGS. 18C and 18D may comprise anymetallic material. The metallic material may comprise a pure metal or ametal alloy. The metallic material may, for example, comprise Pd/Ni, Co,CoW, CoWP, NiB, Ni, NiP, Sn, Ag, Au, Pd, Cu or a combination or sandwichof two or more of these materials (for example, PdNi, Ni/Pd, NiPd/Pd/Au,NiP/Ni/Pd/Au, etc). Generally, the third metal layer may have anythickness. In one or more embodiments, the thickness of the third metallayer 330 may be about 500 nm or greater. The thickness of the thirdmetal layer may even reach about 5000 nm

In the embodiment shown, the third metal layer 330 is thinner than thesecond metal layer 280. Hence, the embodiment shows how a thinner metallayer may be formed over a thicker metal layer. However, in anotherembodiment, it is possible that the third metal layer is thicker thanthe second metal layer. Likewise, in another embodiment, it is possiblethat the third metal layer 330 has about the same thickness as thesecond metal layer 280. In another embodiment, it is also possible thatthe third metal layer 330 be formed over the first metal layer 260.

In the embodiments shown in FIGS. 9, 16A, 17A, and 18A the first metallayer 260 may be formed before the second metal layer 280. In theembodiment shown, the first metal layer 260 is thinner than the secondmetal layer 280. However, in one or more embodiments, it is alsopossible that the first metal layer be thicker than the second metallayer so that the thicker layer is formed before the thinner layer.Hence, in one or more embodiments of the invention the metal lineshaving different thickness may be formed by first depositing a thickmetal layer and then depositing a thin metal layer in a downstreamprocessing step.

Generally, two or more metal layers (such as first metal layer 260,second metal layer 280 and third metal layer 330 as shown in FIG. 18D)to form a final metal layer having a plurality of final metal lines witha plurality of thicknesses. Each of the final metal lines may bespacedly disposed from the other final metal lines. Each of the finalmetal lines may be electrically isolated from the other metal lines. Twoor more of the final metal lines may be electrically coupled together.Two or more may be coupled to the same ground or to the same potential).The final metal layer may have final metal lines with two, three, four,five or more thicknesses.

FIG. 19 shows an embodiment of a structure of the present inventionwherein a metallization layer includes a metal line M1 having athickness T1, a metal line M4 with a thickness T4 and a metal line T5with a thickness T5. In the embodiment shown, the thickness T5 isgreater than the thickness T4 which is greater than the thickness T1.The metal line M1 is formed from first metal layer 260. The metal lineM4 is formed from the second metal layer 280. The final metal line M5 isformed from both the second metal layer 280 and the third metal layer330. Hence, this is an example of a metallization layer having metallines with three different thicknesses. In one or more embodiments, themetallization layer may be a final metal layer. Likewise, the metallines M1, M4 and M5 may be final metal lines.

Another embodiment of is shown in FIGS. 20A through 20G. The embodimentshows an example of a final metal layer comprising a metal line M6 thathas a plurality of portions having different thicknesses. The metal lineM6 is formed from a first metal layer 260 (that includes a first portion260A and a second portion 260B) and a second metal layer 280. FIG. 20Ashows a top view of the metal line M6. FIG. 20G shows a cross sectionalview of metal line M6 through X-X that shows the substrate 210, thelayer 220, the barrier layer 230 and the seed layer 240 (e.g. metallicseed layer).

The metal line M6 may be formed in different ways. In one or moreembodiment, the metal line M6 may be formed by depositing a firstgalvanic resist over the seed layer 240, patterning the first galvanicresist to form openings in the first resist, depositing the first metallayer 260 by an electroplating process to form portions 260A and 260B,removing the first galvanic resist, depositing a second galvanic resist,patterning the second galvanic resist to form an opening in the secondgalvanic resist, depositing the second metal layer 280, and removing thesecond galvanic resist. Referring to FIGS. 20A and 20F, it is seen thata portion of layer 280 overlies a portion of layer 260.

Referring to FIG. 20A, it is seen that the portions 260A and 260B of thefirst metal layer 260 each has a width W₂₆₀. The metal layer 280 has awidth W₂₈₀. In the embodiment shown, the width W₂₈₀ of the second metallayer 280 is larger than the then width W₂₆₀ of the first metal layer260. However, in other embodiments, the width of first metal layer 260may be greater than the width of second metal layer 280. Likewise, inother embodiments, the width of first metal layer 260 may the same asthe width of second metal layer 280.

Referring to FIG. 20B, the portions 260A and 260B of the first metallayer 260 each has a length L₂₆₀. Referring to FIG. 20C, the secondmetal layer 280 has a length L₂₈₀. In the embodiment shown, it is seenthat the length L₂₈₀ of metal layer 280 has a bend. In the embodimentshown, the length of the metal layer 280 is greater than the length ofeach of the portions 260A and 260B of the metal layer 260. But, in otherembodiments, the length of the metal layer 280 may be less than thelength of one or both of the portions 260A, 260B of the metal layer 260.

The total lengthwise direction of the metal line M6 may be viewed as thecombination of the length L₂₆₀ of metal layer 260 and length L₂₈₀ ofmetal layer 280. This is shown as length L_(M6) that is shown in FIG.20D.

Referring to FIG. 20G it is seen that the metal layer 280 has athickness T₂₈₀. In addition, the portions 260A and 260B of metal layer260 each have a thickness T₂₆₀. Referring to FIGS. 20E and 20G, it isseen that the metal line M6 comprises a first portion P1 that includesonly the first metal layer 260 having a first thickness T₂₆₀. The metalline M6 comprises a second portion P2 that includes only the secondmetal layer 280 having a second thickness T₂₈₀. The metal line M6 alsoincludes a third portion P3 where the second metal layer 280 overlapsthe first metal layer 260. This portion P3 includes both the first metallayer 260 and the second metal layer 280. This portion P3 has athickness T_(OVERLAP) which may be essentially equal to the combinedthickness of the first metal layer 260 and the second metal layer 280.The thickness of the entire line M6 is considered to be the maximum ofthe thicknesses of the portions P1, P2 and P3. Hence, the thickness ofthe entire line M6 has a thickness T6 which is equal to the thicknessT_(OVERLAP).

Hence, the metal line M6 comprises three portions with three differentthicknesses. More generally, in one or more embodiments, a metal linemay have a plurality of portions where each portion has a differentthickness. In one or more embodiments, the thickness may change alongthe width of the metal line. An example of this embodiment is shown asmetal line M3 shown in FIG. 17C. In one or more embodiments, thethickness may change along the length of the metal line. An example ofthis embodiment is shown as metal line M6 in FIG. 20A. In one or moreembodiments, it is also possible that the thickness changes in thedirection along the width of the metal line and in the direction alongthe length of the metal line.

A metal line such as the metal line M6 shown in FIG. 20A may be useful.For example, referring to FIG. 20F, it is seen that one end of thethicker portion 280 may be electrically coupled to a power supply 500.The power from the power supply 500 may be distributed from the thickerportion 280 to the thinner portions 260. The thinner portions may beused to distribution the power to logic or analog circuits 600.

In one or more embodiments, it is possible to form a single metal linethat comprises a plurality of portions. Each of the portions may havedifferent thickness. Generally, metal lines may be formed that have anyshape. As one example, they may be straight. As another example, theymay be bent.

All of the concepts described above may be useful for the formation of afinal or top metal layer and for the formation of final or top metallines of a semiconductor chip or device. However, it is understood thatthe discussion is applicable to the metallization layer of anymetallization level of a semiconductor chip, a semiconductor deviceand/or a semiconductor structure. In one or more embodiments,metallization layers may, for example, be referred to as Metal-1,Metal-2, and so on.

It is noted that all of the metal layers described herein may compriseany metallic material. All of the metal layers described herein such as,without limitation, the metal seed layer (such as metal seed layer 240shown in FIG. 7), the first metal layer (such as first metal layer 260shown in FIG. 7), the second metal layer (such as second metal layer 280shown in FIG. 8) as well as the third metal layer (such as third metallayer 330 shown in FIG. 18C) may comprise any metallic material. Themetallic material may be a pure metal or an alloy. In one or moreembodiments, it is possible that a pure metal may include trace amountsof impurities.

The metallic material may be an alloy. The alloy may comprise two ormore metallic elements. The alloy may consist essentially of two or moremetallic elements. The alloy may comprise a metallic element and anon-metallic element. In one or more embodiments, the alloy may, forexample, be steel. The alloy may comprise the element carbon. Examplesof pure metals include, but are not limited to, pure copper, pure gold,pure silver, pure aluminum and pure tungsten. Examples of metals includemetallic copper, metallic gold, metallic silver, metallic aluminum andmetallic tungsten. Examples of alloys include, but are not limited to,copper alloys, gold alloys, silver alloys, aluminum alloys and tungstenalloys. An example of an alloy is a copper aluminum alloy. The metallicmaterial may comprise pure copper or a copper alloy. The metallicmaterial may comprise the element copper (the element Cu). The metalseed layer, the first metal layer, the second metal layer and the thirdmetal layer may all be formed of the same material or they (e.g. two ormore of the layers) may be formed of different materials. One or more ofthe layers may be formed as a heterogeneous mixture of two or morematerials. One or more of the layer may be a composite material. One ormore of the layers may be formed as two or more sub-layers.

Hence, one or more embodiments may be a semiconductor chip and/orsemiconductor device and/or semiconductor structure having ametallization layer comprising a plurality of metal lines having aplurality of thicknesses. The metal lines may all be spacedly disposedfrom each other. The metal lines may all be electrically isolated fromeach other. In one or more embodiments, the final metal layer mayinclude a plurality of metal lines having the same thickness. Themetallization layer may be a final or top metal layer. The metal linesmay be final or top metal lines.

It is noted that the metal lines (such as final metal lines) asdescribed herein may have any widths. In one or more embodiments, thethicker metal lines may have a wider width than a thinner line. However,this does not have to be the case. It may also be possible that athicker line be narrower than a thinner line.

As an example, the metallization layer (such as final or top metallayer) may have at least one thicker metal line and at least one thinnermetal line. In one or more embodiments, there may be at least twothicker metal lines. In one or more embodiments, there may be at leastone thin metal line. The thicker and thinner metals may all be spacedlydisposed from each other. The thicker and thinner metal lines may all beelectrically isolated from each other.

A semiconductor device and/or a semiconductor chip and/or asemiconductor structure having a metallization layer (such as a final ortop metal layer) with a plurality of metal lines (such as final or topmetal lines) with a plurality of thicknesses (for example, with boththicker and thinner metal lines) may have many applications. Forexample, semiconductor devices and chips in Smart Power technologies mayinclude DMOS transistors which require relatively thick metal lines(such as final metal lines). Such lines may require a relatively widepitch (distance between lines). On the other hand, the samesemiconductor devices and chips may include logic applications whichrequire a metallization system with a relatively fine or narrow pitch.For the logic applications, thinner metal lines (such as thinner finalmetal lines) may be better suited so as to accommodate a finer pitch.

It is to be understood that the disclosure set forth herein is presentedin the form of detailed embodiments described for the purpose of makinga full and complete disclosure of the present invention, and that suchdetails are not to be interpreted as limiting the true scope of thisinvention as set forth and defined in the appended claims.

What is claimed is:
 1. A method for forming a first metal line and asecond metal line of a semiconductor device, comprising: providing asurface, wherein the surface is planar; forming a first metal layer overa portion of said surface; and forming a second metal layer comprisingforming a first portion of the second metal layer over at least oneportion of said first metal layer and forming a second portion of thesecond metal layer in direct contact with a portion of said surface thatis not occupied by said first metal layer, the second portion of thesecond metal layer being spaced apart from the first portion of thesecond metal layer, wherein a gap through the second metal layerseparates the first portion of the second metal layer from the secondportion of the second metal layer so that the first and second portionsof the second metal layer are discrete; wherein the first portion of thesecond metal layer is further formed directly on a portion of thesurface, wherein the second portion of the second metal layer has auniform thickness that is greater than a thickness of the first metallayer, the thicknesses of the first and second metal layers beingmeasured in a direction perpendicular to the provided surface, whereinthe first metal line is formed by the first metal layer and the firstportion of the second metal layer, and wherein the second metal line isformed by the second portion of the second metal layer.
 2. The method ofclaim 1, wherein said surface is the surface of a metal seed layer. 3.The method of claim 1, wherein said first metal layer is formed by anelectroplating process.
 4. The method of claim 1, wherein said secondmetal layer is formed by an electroplating process.
 5. The method ofclaim 1, wherein said first metal layer comprises the element copper andsaid second metal layer comprises the element copper.
 6. The method ofclaim 1, wherein the first portion of the second metal layer is formeddirectly on the at least one portion of the first metal layer.
 7. Themethod of claim 1, wherein the second portion of the second metal layerdoes not physically contact the first metal layer.
 8. The method ofclaim 1, further comprising covering a plurality of sidewalls of thesecond portion of the second metal layer with a passivation layer. 9.The method of claim 1, further comprising depositing a passivation layerat least partially in the gap through the second metal layer between thefirst portion and the second portion of the second metal layer.
 10. Amethod for forming a first metal line and a second metal line of asemiconductor device, comprising: providing a surface; forming a firstmetal layer over a first portion of said surface; and forming a secondmetal layer comprising forming a first portion of the second metal layerover at least one portion of said first metal layer and forming a secondportion of the second metal layer in direct contact with a secondportion of said surface that is not occupied by said first metal layer,the second portion of the second metal layer being spaced apart from thefirst portion of the second metal layer, wherein the first portion andthe second portion of said surface are at a same height level, andwherein a gap through the second metal layer separates the first portionof the second metal layer from the second portion of the second metallayer so that the first and second portions of the second metal layerare discrete; wherein the first portion of the second metal layer isfurther formed directly on a portion of the surface, wherein the secondportion of the second metal layer has a uniform thickness that isgreater than a thickness of the first metal layer, the thicknesses ofthe first and second metal layers being measured in a directionperpendicular to the provided surface, and wherein the first metal lineis formed by the first metal layer and the first portion of the secondmetal layer, and wherein the second metal line is formed by the secondportion of the second metal layer.
 11. The method of claim 10, whereinsaid surface is the surface of a metal seed layer.
 12. The method ofclaim 10, wherein said first metal layer is formed by an electroplatingprocess.
 13. The method of claim 10, wherein said second metal layer isformed by an electroplating process.
 14. The method of claim 10, whereinsaid first metal layer comprises the element copper and said secondmetal layer comprises the element copper.
 15. The method of claim 10,wherein the first portion of the second metal layer is further formeddirectly on a portion of the surface.
 16. The method of claim 10,wherein the first portion of the second metal layer is formed directlyon the at least one portion of the first metal layer.
 17. The method ofclaim 10, wherein the second portion of the second metal layer isthicker than the first metal layer in a direction perpendicular to thesurface.